Coating composition comprising autoxidisable component

ABSTRACT

An aqueous emulsion coating composition comprising an autoxidisable vinyl oligomer having ≧20 wt % of unsaturated fatty acid residue; Tg from −50 to +15° C.; Mw from 2,500 to 40,000 g/mol; polydispersity from 2 to 12, said composition having ≦15% co-solvent by weight of solids, ≦13% NMP by weight of solids ≧38% solids by weight of composition; said composition when in the form of a coating having a telegraphing value defined as the difference in gloss at a 20° angle of between a film cast on rough PVC and a film cast on smooth PVC of 10 gloss units.

This application is a continuation of commonly owned copending U.S.application Ser. No. 12/919,278, filed Dec. 20, 2010 (now abandoned),which is the national phase application under 35 USC §371 ofPCT/EP2009/053829, filed Mar. 31, 2009, and claims the benefit ofpriority of EP 08006274.8, filed Mar. 31, 2008, the entire contents ofwhich is hereby incorporated by reference.

The present invention relates to certain coating compositions thatcomprise an autoxidisable component and processes for making suchcompositions. Coatings of the invention show reduced telegraphing ofsurface irregularities after the composition has been applied to asurface.

There is a general need when applying a decorative or protective coatingto a substrate to obtain a smooth surface without visibleirregularities. The degree to which an underlying surface can bevisually ascertained through a coating is often described astelegraphing (i.e. giving a clumsily obvious hint or prematureindication of something to come). It has been found that irregularitieson substrates (such as wood), which contribute to the roughness, areoften telegraphed through conventional dry coatings.

Thicker coating materials are often used to reduce telegraphing becausethey are sufficiently able to level out any unevenness in the surface.Thus the underlying surface roughness of the substrate shows through toa reduced extent into the final coating which appears visually smooth.However, thicker coatings are disadvantageous because they may need tobe applied in several layers, increasing the cost. Also slowerthrough-drying, wrinkling and sagging can occur when using thickerlayers.

Organic solvents have been used to reduce telegraphing. However with acontinuing concern about the use of organic solvents there has been along felt need for an aqueous coating composition with comparableproperties to those achievable using compositions based on organicsolvents.

A coating should also dry sufficiently quickly to avoid the adherence ofdust and to ensure that the coating quickly becomes water resistant(e.g. in case of outdoor applications), blocking resistant andtack-free.

Aqueous compositions such as water dilutable autoxidisable esters (alsoknown as water dilutable unsaturated alkyds or alkyd emulsions) havealso been used to address the issue of telegraphing. However thesesystems have many well known problems.

Water dilutable alkyds may also suffer from backbone hydrolysis. Thismay lead to changes in the performance over time which is undesirable.Traditional alkyd emulsions are discussed in “Water borne and solventbased alkyds and their end user applications” by N. Tuck, volume VI,Wiley/Sita Series In Surface Coatings technology; (ISBN 471985910)published in 2000.

Another common problem of traditional alkyd emulsions is their tendencyto produce cissing (also known as crawling) when applied as anover-coat. Cissing is when a coating refuses to form a continuous film,recedes from the surface, collects in beads and leaves the surfacepartially exposed thus reducing the appearance of the painted object.

Yet another disadvantage of traditional alkyd systems, especially thosecontaining a relatively high percentage of unsaturated fatty acidresidues, is their pronounced tendency to yellow (in light or dark) overtime.

Current coatings lack some or all of the above mentioned performancecharacteristics, so coatings which exhibit reduced telegraphing with acombination of: minimal hydrolysis of the backbone of the alkyd, lowyellowing over time and/or reduced cissing are desired.

Prior aqueous coatings have not been widely accepted in many markets asalternatives to solvent based coatings. For example solvent based alkydsare still preferred in the decorative market, where very lowtelegraphing is required as these coatings are often applied by brush.It is also desired that aqueous compositions are not milky or opaque butclear or transparent.

It is also generally known that polyester based alkyds (PE alkyds)typically have a broad molecular weight distribution and thus comprise asignificant amount of material having a low molecular weight, whichdries more slowly and therefore means the coating remains tacky for alonger period (i.e. has long tack free times). The presence of materialof lower molecular weight cannot be avoided for many reasons. Forexample both glycerol (with three fatty acids—triglycerides) andpentaerythritol (with four fatty acids) are common raw materials used toprepare PE alkyds. To address the issues raised by the presence of thelow molecular weight fraction, PE alkyds may be prepared in a highlybranched form to obtain a high molecular weight fraction that dries morequickly. However the resultant branched PE alkyds have a significantlyincreased viscosity and reduced flow (compared to less branchedequivalents) and thus must be diluted with more organic solvent beforethey can be used. This is undesirable as for example it increases theamount of volatile organic compounds (VOC) and adversely affects theflow of the composition.

It is known that autoxidisable vinyl polymers may be prepared by aradical polymerisation of vinyl monomers in the presence of a fatty acidderivative. However the resultant polymers have a broad molecular weightdistribution, and these polymers require higher amounts of solvent tomake a coating, which generally also contains high levels of freemonomer. Without wishing to be bound by theory it is believed thatunsaturated fatty acids retard radical polymerisation and graft onto thevinyl polymer resulting in more material of higher molecular weight anda broader molecular weight distribution.

WO 2002-033012 (=EP 1328594) (Avecia) discloses an aqueous coatingcomposition based on a cross-linkable water-dispersible vinyl oligomerand optionally a dispersed polymer. The oligomers described in thisapplication have a low amount of fatty acid (<40% by weight). As shownby the comparative data herein these oligomers are designed for adifferent purpose (improved open time) and produce coatings which,within a few days, lack satisfactory body (in the tests as definedherein), do not produce satisfactory tack free times. The acidfunctional acrylates described also contain high levels of NMP whichwill reduce the rate of curing and may contribute to yellowing.

U.S. Pat. No. 5,089,342, EP 0370299 and EP 0316732 (all Bayer) disclosean aqueous, air drying coating composition containing a water-soluble,air-drying polyacrylate with a molecular weight of more than 1000 g/moleand 5-40 wt % of chemically incorporated fatty acids and 50-100milli-equivalents per 100 grams of solid of chemically incorporatedquaternary ammonium moieties. This reference describes systems that arecationic, teaching away from using anionic systems (e.g. see col. 1,line 53) and teaches use of styrenic monomers as part of the vinylmonomers which is not ideal as it can cause yellowing in the finalproduct.

U.S. Pat. No. 5,096,959 (Valspar) discloses water based alkyd resinsthat are modified to provided increased hydrolytic stability by reactingthem with a polybasic acid composition containing one or morecyclo-aliphatic polybasic acids.

WO 2007-147559 (DSM) describes air drying fatty acid functionalhyper-branched resins. The resins are water soluble, due to a relativelyhigh OH content and a low fatty acid level. This is less desirable dueto the effect it has on water resistance and rate of cure and thereforeon final properties.

US 2004-198903 discloses an ambient curable aqueous dispersion ofpolymer particles containing pendant ethylenically unsaturated sidechains.

U.S. Pat. No. 6,653,381 discloses fatty acid functional vinyl polymersobtained by copolymerisation of fatty acid functional vinyl monomers.The low levels of fatty acid used may lead to insufficient flow duringdrying and slow cure rates.

EP 425085 discloses water based autoxidisable coating compositionscomprising a partially esterified carboxylic acid functional filmforming copolymer derived from olefinically unsaturated monomers. Thisreference teaches that it is essential for all or most of theautoxidisable groups to be 3-allyloxy-2-hydroxypropyl groups (or the3-alkylallyl or butyl analogues) for the copolymer to retain a highdegree of water solubility. This may result in a low cure rate and theallyl groups have been reported to release toxic compounds during cure.

JP 60110765 discloses the reaction of copolymer of an alpha betaunsaturated acid, such as acrylic acid and other monomers with aglycidyl ester of unsaturated fatty acid to form a resin which iscombined with a second resin to give a thick aqueous coating.

We have now found ways to overcome the above mentioned disadvantages,especially when combinations of more then one of the problems need to beovercome in one coating system.

It is an object of the invention to solve some or all or the problemsidentified herein. A preferred object of the invention provides a methodof improving the appearance of coated substrates, the substratescontaining visual irregularities. In a more preferred object of theinvention the method can be used with a wide variety of coatingcompositions.

The applicant has found that certain vinyl polymers prepared by radicalpolymerisation of certain vinyl/acrylic monomers may comprisesignificantly less low molecular weight fraction (like theaforementioned triglycerides) avoiding the need to use significantamounts of high molecular weight material, for example to improvedrying. The applicant has also surprisingly found that certain vinylpolymers (with specific molecular weight, PDi and T_(g) values), thatare prepared by radical polymerisation of epoxy functional vinylmonomers with other vinyl monomers, and then reacted with certainunsaturated fatty acids may overcome some or all of the above identifiedproblems with prior art vinyl polymers.

According to the present invention there is provided an aqueousemulsion, coating composition that comprises an autoxidisable vinyloligomer where:

-   -   I) said autoxidisable vinyl oligomer has:        -   i) fatty acid residue in an amount greater than or equal to            20% by weight of the autoxidisable vinyl oligomer;        -   ii) a glass transition temperature (T_(g)) from −50° C. to            +15° C.;        -   iii) an acid value less than 40 mg KOH/g;        -   iv) a weight average molecular weight (M_(w)) from 2,500 to            40,000 g/mol;        -   v) a polydispersity (PDi) from 2 to 12;    -   II) said composition has:        -   a) a co-solvent content less than 25% by weight of solids;        -   b) a N-methylpyrrolidone content less than 13% by weight of            solids;        -   c) a solids content greater than or equal to 38% by the            total weight of said composition; and    -   III) said composition when in the form of the film has a        telegraphing value of less than 10 gloss units,        -   where the telegraphing value is the difference between an            initial smooth gloss value minus an initial rough gloss            value of the film, where        -   the initial smooth gloss value is the gloss when the film is            cast on smooth PVC (R_(z)=1 μm [±0.25 μm]);        -   the initial rough gloss value is the gloss when the film is            cast on rough PVC(R_(z)=25 microns [μm] [±5 μm]); and where        -   each film has a dry film thickness of 52 μm [±6 μm]; and        -   each initial gloss value is measured at a 20° angle, one day            (24 hours) after the film has been cast.

As used herein PVC means a polyvinylchloride substrate used as describedin the test methods herein.

Dry film thickness is measured herein after 24 hours of drying, understandard conditions. As used herein, unless the context indicatesotherwise, the terms ‘standard conditions’ denotes a relative humidityof 50%±5%, ambient temperature and an air flow less than or equal to 0.1m/s; and ‘ambient temperature’ denotes 23° C.±2°.

The telegraphing values herein will be positive numbers. In general thegreater the reduction in telegraphing, the smaller will be thetelegraphing value.

The term “comprising” as used herein means that the list thatimmediately follows is non exhaustive and may or may not include anyother additional suitable items, for example one or more furtherfeature(s), component(s), ingredient(s) and/or substituent(s) asappropriate. “Substantially comprising” as used herein means a componentor list of component(s) is present in a given material in an amountgreater than or equal to about 90%, preferably ≧95%, more preferably≧98% by weight of the total amount of the given material. The term“consisting of” as used herein mean that the list that follows isexhaustive and does not include additional items.

For all upper and lower boundaries of any parameters given herein, theboundary value is included in each range for each parameter. Allcombinations of minimum and maximum values of the parameters describedherein may be used to define the parameter ranges for variousembodiments and preferences of the invention.

It will be understood that the total sum of any quantities expressedherein as percentages cannot (allowing for rounding errors) exceed 100%.For example the sum of all components of which the composition of theinvention (or part(s) thereof) comprises may, when expressed as a weight(or other) percentage of the composition (or the same part(s) thereof),total 100% allowing for rounding errors. However where a list ofcomponents is non-exhaustive the sum of the percentage for each of suchcomponents may be less than 100% to allow a certain percentage foradditional amount(s) of any additional component(s) that may not beexplicitly described herein.

As used herein the terms oligomer and polymer both refer tomacromolecules which comprises a plurality of units derived, actually orconceptually, from molecules of lower molecular mass. These terms mayalso be used adjectivally to describe a part or the whole of amacromolecule. Often the term oligomer may be used more specifically torefer to macromolecules of intermediate relative molecular mass, wherethe oligomer properties vary significantly with the removal of one or afew units. Polymer may be used both generally to refer to anymacromolecule and also more specifically to refer to macromolecules ofhigh relative molecular mass where usually addition or removal of one ora few units has a negligible effect on the molecular properties(although this may not be always be the case for example where polymershave certain properties that are critically dependent on fine details ofthe molecular structure). It will be understood that the molecular massboundary between an oligomer and a polymer (in its specific rather thangeneral meaning) may vary according to the specific macromolecule and/orapplications of interest and so they may be significant overlap wherethe same macromolecules may be considered both a oligomer and a polymer.Therefore, unless the context herein clearly indicates otherwise, theterms oligomer and polymer are used herein interchangeably.

Preferably each of the coating compositions of the invention arenon-adhesive compositions. As used herein the term ‘non-adhesivecomposition’ denotes any composition that does not remain substantiallytacky after drying under ambient conditions for a length of time whichwould be commercially acceptable. Non-adhesive compositions may be thosewhich have a tack-free time of less than or equal to 16 hours,preferably ≦10 hours, more preferably ≦6 hours, most preferably ≦4hours. Tack free time may conveniently be measured as described herein.

Preferred compositions of the invention produce coatings that have atelegraphing value (as defined herein) of less than 7 gloss units, morepreferably less than 4 gloss units and most preferably less than 2 glossunits.

Preferably the initial rough gloss should not deteriorate significantlyover time. This can be measured as a ‘gloss decay’ defined as theinitial rough gloss minus a rough gloss measured at a later specifiedtime. For example “gloss decay (‘n’ days)” is calculated as the initialrough gloss (measured 1 day after film formation) minus the rough glossmeasured ‘n’ days after film formation (i.e. in this case n isalways >1). Preferably the gloss decay is measured 4 days, morepreferably 7 days and most preferably 14 days after film formation.Preferred values of gloss decay (for example after each of the periodsgiven above) are less than 14 gloss units, more preferably less than 10gloss units, most preferably less than 7 gloss units and especially lessthan 4 gloss units.

Without wishing to be bound by any theory it is believed that the vinylpolymers of the invention have a comb like structure allowing excellentcontrol of molecular weight distribution to give a relatively narrowdistribution resulting in good flow, reduced telegraphing and fastdrying. Conventional vinyl polymers are typically highly branched andused under conditions which are close to those which cause the polymerto gel. In contrast the vinyl polymers of the invention arehydrolytically stable as their backbone is more resistant to hydrolysis.These properties are especially important for decorative paints whichmay stay on the shelf for a long time.

Polymers of the invention have a narrow molecular weight distribution(PDi) and a relatively low weight average molecular weight (M_(w)) andtherefore an improved balance between M_(w) and PDi. As such polymershave less material of low molecular weight, coating compositions of theinvention (comprising such polymers) can dry fast, for example haveshort dust and/or tack free times. Aqueous compositions of the inventionhave other advantages. They may be prepared with lower viscosity due tothe reduced amount of high molecular weight material and lower viscositycan reduce telegraphing. Compositions of the invention can also beprepared with a high solids content.

Preferably the autoxidisable vinyl polymer will cross-link at ambienttemperature. Cross-linking by autoxidation means the cross-linkingresults from an oxidation occurring in the presence of air, usuallyinvolving a free radical mechanism and is preferably metal-catalysedresulting in covalent bonds. Suitable autoxidation is provided by forexample fatty acid residues comprising unsaturated bonds, allylfunctional residues and/or β(beta)-keto ester groups, preferably byfatty acid residues comprising unsaturated bonds.

As used herein ‘fatty acid residue’ (or FA residue), means fatty acids,simple derivatives thereof (such as esters (e.g. C₁₋₄alkyl esters),salts, soaps, oils, fats and/or waxes) and mixtures thereof. As usedherein ‘fatty acid’ means any predominately unbranched, non-cyclic(preferably substantially linear) aliphatic carboxylic acid thatsubstantially comprises, preferably consists of an aliphatic hydrocarbonchain and at least one carboxy group, preferably a single terminalcarboxyl group (i.e. located at the end of the chain). Fatty acids maycomprise a limited number of other substituents such as hydroxyl and maybe saturated, mono-unsaturated or poly-unsaturated.

The fatty acid residue may be obtained from one or more natural and/orartificial source. Natural sources include animal sources and/or plantsources. Animal sources may comprise animal fat, butter fat, fish oil,lard, liver fats, sperm whale oil and/or tallow oil and waxes. Examplesof waxes are beeswax, candelia and/or montan. Plant sources may comprisewaxes and/or oils such as vegetable oils and/or non-vegetable oils.Examples of plant oils are: bitter gourd, borage, calendula, canola,castor, china wood, coconut, conifer seed, corn, cottonseed, dehydratedcastor, flaxseed, grape seed, Jacaranda mimosifolia seed, linseed,olive, palm, palm kernel, peanut, pomegranate seed, rapeseed, safflower,snake gourd, soya(bean), sunflower, tung, and/or wheat germ. Artificialsources include synthetic waxes (such as micro crystalline and/orparaffin wax), distilling tall oil (a by-product of processing pinewood) and/or synthesis (for example by chemical and/or biochemicalmethods). Fatty acid residues having conjugated double bonds may beobtained by catalytic isomerisation of natural fatty acids and/ordehydrated castor oil. Conjugated oils are preferably obtained bydehydration of castor oil. Fatty acid residues may be obtained and/orobtainable from a plurality of the above sources and/or other sourcesnot listed herein.

Preferred fatty acid residues may comprise fatty acid(s) having from 4to 36, more preferably from 8 to 26, most preferably from 10 to 24,especially 12 to 22 carbon atoms. Generally fatty acids obtained fromnatural sources have an even number of carbon atoms due to their methodof bio-synthesis, however fatty acids with an odd number of carbon atomsmay also be useful in the present invention. Fatty acid residues maycomprise fatty acids with one or more carboxylic acid groups, forexample dimer or trimer fatty acids. Preferred fatty acids are monofunctional, more preferably C₁₀₋₂₄mono functional carboxylic acids, mostpreferably C₁₂₋₂₂ linear mono functional terminal carboxy acids.

As long as oxidative drying of the polymer is not impaired the fattyacid residue may comprise one or more saturated fatty acids and/or oils,however at least some unsaturated fatty acid(s) is needed forauto-oxidation to occur. In general the more unsaturation present themore rapid the autoxidiative drying.

An iodine number may be used to indicate the amount of unsaturationcontained in fatty acids where a higher the iodine number indicates moreunsaturated double bonds are present. Preferably the fatty acid residueused herein has an average iodine value greater than or equal to 50,more preferably ≧80 and most preferably ≧100 g I₂/100 g fatty acid.Preferably the fatty acid residue used herein has an average iodinevalue less than or equal to 200, more preferably ≦180 and mostpreferably ≦150 g I₂/100 g fatty acid. The iodine value may be measuredconventionally or preferably as described in the test methods herein.

For the purpose of determining the amount of fatty acid residue used toobtain the vinyl polymer of the invention, it is convenient to calculatethe weight of the fatty acid reactant by including the carbonyl group,but excluding the hydroxyl group of the terminal acid group of the fattyacid molecule.

Preferably the minimum amount of fatty acid residues in theautoxidisable vinyl polymer is greater than or equal to 30%, morepreferably ≧38%, most preferably ≧43% and especially ≧50% by weight ofthe polymer.

Preferably the maximum amount of fatty acid residue in the autoxidisablevinyl polymer is less than or equal to 70%, more preferably ≦65%, mostpreferably ≦59% by weight of the polymer.

Preferably the fatty acid residue comprises C₁₀₋₃₀ fatty acids, morepreferably C₁₆₋₂₀ fatty acids, in an amount greater than or equal to 80%by weight of the fatty acid residue. More preferably the fatty acidresidue substantially comprises, most preferably consists of C₁₀₋₃₀fatty acids, especially C₁₆₋₂₀ fatty acids.

If the fatty acid residue comprises saturated fatty acids they may bepresent in an amount less than or equal to 40%, more preferably 20% andmost preferably from 3% to 18% by weight of the fatty acid residue.

Preferred vinyl polymers are those in which the autoxidisable groups aremainly derived from fatty acid residue. More preferably the fatty acidresidue mainly comprises, most preferably substantially comprisesunsaturated fatty acids. Useful unsaturated fatty acids have two or moredouble bonds and more usefully are conjugated fatty acids.

Preferably at least 40% by weight, more preferably at least 60% byweight of the unsaturated fatty acids in the fatty acid residue arefatty acids that contain at least two ethylenically unsaturated groups(i.e. are polyunsaturated).

Preferred fatty acid residues comprise at least one conjugated fattyacid. The total amount of conjugated fatty acid may be greater than 0%,preferably ≧10% by weight of the unsaturated fatty acid. The totalamount of conjugated fatty acid may be less than or equal to 70%,preferably ≦55%, more preferably ≦40%, by weight of the unsaturatedfatty acid. The autoxidisable vinyl polymer may be obtained from amixture of conjugated and non-conjugated unsaturated fatty acids.

A known problem with many autoxidisable coating compositions is that theresultant coatings have a tendency to yellow, in particular where theautoxidisable groups are derived from polyunsaturated fatty acids (e.g.those described herein). This may be unacceptable depending on thedesired color of the resultant coating.

Therefore in another embodiment of the invention to reduce yellowing,preferred autoxidisable vinyl polymers are those where the unsaturatedfatty residue comprises low amounts of highly polyunsaturated fattyacids. For example vinyl polymers that are more resistant to yellowingmay be obtained and/or obtainable from fatty acid residue that compriseby weight of total fatty acid less than or equal to 10%, more preferably≦7%, most preferably ≦4% and especially ≦2% of fatty acids with three ormore double bonds. Examples of fatty acids that include three or moredouble bonds are given herein.

Preferred compositions of the invention have an initial yellowness valueof less than or equal to 10, more preferably ≦7 and most preferably ≦4,when measured using the test method described herein. Preferredcompositions show only a small increase in yellowness (Δb value) afterbeing held in darkness for 3 weeks at 52° C., more preferably Δb is lessthan or equal to 10, still more preferably is ≦7, most preferably ≦5 andespecially ≦3.

In yet another embodiment of the invention (e.g. where yellowing is nota concern) preferred autoxidisable vinyl polymers are those where theunsaturated fatty residue comprises higher amounts of highlypolyunsaturated fatty acids (such as fatty acids with three or moredouble bonds) as this can improve the speed of autoxidative drying.

Preferably the unsaturated fatty acid is covalently bound to the vinylpolymer in a one step process, either though the use of a fatty acidfunctional vinyl monomer or through a reaction of the fatty acid withthe vinyl polymer.

It is preferred that glycidyl esters of unsaturated fatty acids are notused in the preparation of the autoxidisable vinyl polymer as thesynthesis of these glycidyl esters requires toxic raw materials like forinstance epichlorohydrine which will also give chlorine containing wastematerial which is undesirable. A glycidyl ester of an unsaturated fattyacid is an epoxy functional fatty acid material (usually with a numberaverage molecular weight (M_(n)) below 400) where the acid group hasbeen reacted to obtain a glycidyl end group.

Optionally the fatty acid residue may also comprise one or more alkynylgroup(s) and/or one or more (non carboxy) hydroxyl group(s).

Non limiting examples of some common fatty acids that may be used in thepresent invention are listed below as their systematic (IUPAC) nameswith their trivial name(s) in square parentheses where known. It will beappreciated that in practice most fatty acid residues (especially thoseobtained from natural sources) will comprise a mixture of many of theseacids as well as other acids not specifically listed herein.

Saturated fatty acids may be selected from:

butanoic [butyric] acid (C₄H₈O₂), pentanoic [valeric] acid (C₅H₁₀O₂),hexanoic [caproic] acid (C₆H₁₂O₂), heptanoic [enanthic] acid (C₇H₁₄O₂),octanoic [caprylic] acid (C₈H₁₆O₂), nonanoic [pelargonic] acid(C₉H₁₈O₂), decanoic [capric] acid (C₁₀H₂₀O₂), dodecanoic [lauric] acid(C₁₂H₂₄O₂), tetradecanoic [myristic] acid (C₁₄H₂₈O₂), hexadecanoic[palmitic] acid (C₁₆H₃₂O₂), heptadecanoic [margaric also daturic] acid(C₁₇H₃₄O₂), octadecanoic [stearic] acid (C₁₈H₃₆O₂), eicosanoic[arachidic] acid (C₂₀H₄₀O₂), docosanoic [behenic] acid (C₂₂H₄₄O₂),tetracosanoic [lignoceric] acid (C₂₄H₄₈O₂), hexacosanoic [cerotic] acid(C₂₆H₅₂O₂), heptacosanoic [carboceric] acid (C₂₇H₅₄O₂), octacosanoic[montanic] acid (C₂₈H₅₆O₂), triacontanoic [melissic] acid (C₃₀H₆₀O₂),dotriacontanoic [lacceroic] acid (C₃₂H₆₄O₂), tritriacontanoic[ceromelissic also psyllic] acid (C₃₃H₆₆O₂), tetratriacontanoic [geddic]acid (C₃₄H₆₈O₂) and/or pentatriacontanoic [ceroplastic] acid (C₃₅H₇₀O₂).

Mono-unsaturated fatty acids may be selected from:

(Z)-decan-4-enoic [obtusilic] acid (C₁₀H₁₈O₂), (Z)-decan-9-enoic[caproleic] acid (C₁₀H₁₈O₂), (Z)-undecan-10-enoic [undecylenic also10-hendecenoic] acid (C₁₁H₂₀O₂), (Z)-dodan-4-ecenoic [linderic] acid(C₁₂H₂₂O₂), (Z)-dodecan-5-enoic (lauroleic) acid (C₁₂H₂₂O₂),(Z)-tetradecan-4-enoic [tsuzuic] acid (C₁₄H₂₆O₂), (Z)-tetradecan-5-enoic[physeteric] acid (C₁₄H₂₆O₂), (Z)-tetradecan-9-enoic [myristoleic] acid(C₁₄H₂₆O₂), (Z)-hexadan-6-enoic [sapienic] acid (C₁₆H₃₀O₂),(Z)-hexadan-9-enoic [palmitoleic] acid (C₁₆H₃₀O₂), (Z)-octadecan-6-enoic[petroselinic] acid (C₁₈H₃₄O₂), (E)-octadecan-9-enoic [elaidic] acid(C₁₈H₃₄O₂), (Z)-octadecan-9-enoic [oleic] acid (C₁₈H₃₄O₂),(Z)-octadecan-11-enoic [vaccenic also asclepic] acid (C₁₈H₃₄O₂),(Z)-eicosan-9-enoic [gadoleic] acid (C₂₀H₃₈O₂), (Z)-eicosan-11-enoic[gondoic] acid (C₂₀H₃₈O₂), (Z)-docosan-11-enoic [cetoleic] acid(C₂₂H₄₂O₂), (Z)-docosan-13-enoic [erucic] acid (C₂₂H₄₂O₂) and/or(Z)-tetracosan-15-enoic [nervonic] acid (C₂₄H₄₆O₂).

Di-unsaturated fatty acids may be selected from:

(5Z,9Z)-hexadeca-5,9-dienoic acid (C₁₆H₂₈O₂),(5Z,9Z)-octadeca-5,9-dienoic [taxoleic] acid (C₁₈H₃₂O₂),(9Z,12Z)-octadeca-9,12-dienoic [linoleic] acid (C₁₈H₃₂O₂),(9Z,15Z)-octadeca-9,15-dienoic acid (C₁₈H₃₂O₂) and/or(7Z,11Z)-eicosa-7,11-dienoic [dihomotaxoleic] acid (C₂₀H₃₆O₂).

Tri-unsaturated fatty acids may be selected from:

(5Z,9Z,12Z)-heptadeca-5,9,12-trienoic acid (C₁₇H₂₈O₂),(3Z,9Z,12Z)-octadeca-3,9,12-trienoic acid (C₁₈H₃₀O₂),(5Z,9Z,12Z)-octadeca-5,9,12-trienoic [pinolenic] acid (C₁₈H₃₀O₂),(6Z,9Z,12Z)-octadeca-6,9,12-trienoic acid [γ(gamma)-linolenic acid alsoGLA](C₁₈H₃₀O₂), (8E,10E,12Z)-octadeca-8,10,12-trienoic [calendic] acid(C₁₈H₃₀O₂), (8Z,10E,12Z)-octadeca-8,10,12-trienoic [jacaric] acid(C₁₈H₃₀O₂), (9E,11E,13E)-octadeca-9,11,13-trienoic [β(beta)-eleostearicalso 3-oleostearic] acid (C₁₈H₃₀O₂),(9E,11E,13Z)-octadeca-9,11,13-trienoic [catalpic] acid (C₁₈H₃₀O₂),(9Z,11E,13E)-octadeca-9,11,13-trienoic [α(alpha)-eleostearic alsoα-oleostearic] acid (C₁₈H₃₀O₂) (where α-eleostearic acid comprises >65%of the fatty acids of tung oil), (9Z,11E,13Z)-octadeca-9,11,13-trienoic[punicic also trichosanic] acid (C₁₈H₃₀O₂),(9Z,11E,15Z)-octadeca-9,11,13-trienoic [rumelenic] acid (C₁₈H₃₀O₂),(9Z,13E,15Z)-octadeca-9,13,13-trienoic acid (C₁₈H₃₀O₂),(9Z,12Z,15Z)-octadeca-9,12,15-trienoic acid [α(alpha)-linolenic acidalso ALA](C₁₈H₃₀O₂), (5Z,8Z,11Z)-eicosa-5,8,11-trienoic[dihomo-γ(gamma)-linolenic] acid (C₂₀H₃₄O₂),(5Z,11Z,14Z)-eicosa-8,11,14-trienoic [sciadonic] acid (C₂₀H₃₄O₂) and/or(8Z,11Z,14Z)-eicosa-8,11,14-trienoic [Mead] acid (C₂₀H₃₄O₂).

Tetra-unsaturated fatty acids may be selected from:

(6Z,8Z,10Z,12Z)-hexadeca-6,8,10,15-tetraenoic acid (C₁₆H₂₄O₂),(6Z,8Z,10Z,12Z)-octadeca-6,8,10,12-tetraenoic acid (C₁₈H₂₈O₂),(6Z,9Z,12Z,15Z)-octadeca-6,9,12,15-tetraenoic [stearidonic] acid(C₁₈H₂₈O₂), (9Z,11E,13E,15Z)-octadeca-9,11,13,15-tetraenoic[α(alpha)-parinaric] acid (C₁₈H₂₈O₂),(9Z,11Z,13Z,15Z)-octadeca-9,11,13,15-tetraenoic [β(beta)-parinaric] acid(C₁₈H₂₈O₂), (5Z,8Z,11Z,14Z)-eicosa-5,8,11,14-tetraenoic acid[arachidonic acid also AA](C₂₀H₃₂O₂),(6Z,8Z,10Z,12Z)-eicosa-6,8,10,12-tetraenoic acid (C₂₀H₃₂O₂),(8Z,11Z,14Z,11Z)-eicosa-8,11,14,17-tetraenoic acid (C₂₀H₃₂O₂),(6Z,8Z,10Z,12Z)-docosa-6,8,10,12-tetraenoic acid (C₂₂H₃₆O₂) and/or(7Z,10Z,13Z,16Z)-docosa-7,10,13,16-tetraenoic acid (C₂₂H₃₆O₂).

Penta-unsaturated fatty acids may be selected from:

(x,6Z,8Z,10Z,12Z)-hexadeca-x,6,8,10,12-pentaenoic acid(s) (C₁₆H₂₂O₂)where x denotes a fifth double bond optionally in a position which doesnot conjugate with the other four conjugated ethylenic double bonds,(x′,6Z,8Z,10Z,12Z)-eicosa-x′,6,8,10,12-pentaenoic acid(s) (C₂₀H₃₀O₂)where x′ denotes a fifth double bond optionally in a position which doesnot conjugate with the other four ethylenic double bonds,(5E,7E,9E,14Z,17Z)-eicosa-5,8,11,14,17-pentaenoic acid (C₂₀H₃₀O₂),(5Z,7E,9E,14Z,17Z)-eicosa-5,8,11,14,17-pentaenoic acid (C₂₀H₃₀O₂),(5Z,8Z,11Z,14Z,17Z)-eicosa-5,8,11,14,17-pentaenoic acid [EPA](C₂₀H₃₀O₂), (7Z,10Z,13Z,16Z,19Z)-docosa-7,10,13,16,19-pentaenoic[clupanodonic] acid (C₂₂H₃₄O₂),(4Z,7Z,10Z,13Z,16Z)-docosa-4,7,10,13,16-pentaenoic [osbond] acid(C₂₂H₃₄O₂) and/or (7Z,10Z,13Z,16Z,19Z)-docosa-7,10,13,16,19-pentaenoicacid [DPA] (C₂₂H₃₄O₂).

Hexa-unsaturated fatty acids may be selected from:

(x″,y″,6Z,8Z,10Z,12Z)-eicosa-x″,y″,6,8,10,12-hexaenoic acid(s)(C₂₀H₂₈O₂) where x″ and y″ denote fifth and sixth double bondsoptionally in positions which do not conjugate with the other fourconjugated ethylenic double bonds,(4Z,7Z,10Z,13Z,16Z,19Z)-docosa-4,7,10,13,16,19-hexaenoic acid [DHA](C₂₂H₃₂O₂) and/or(6Z,9Z,12Z,15Z,18Z,21Z)-tetracosa-6,9,12,15,18,21-hexaenoic [nisinic]acid (C₂₄H₃₆O₂).

Hepta-unsaturated fatty acids may be selected from:

(w′″,x′″,y′″,6Z,8Z,10Z,12Z)-eicosa-w′″,x′″,y′″,6,8,10,12-heptaenoicacid(s) (C₂₂H₃₀O₂) where w′″, x′″ and y′″ denote fifth, sixth and sevendouble bonds optionally in positions which do not conjugate with theother four conjugated ethylenic double bonds, and/or(4Z,7Z,9Z,11Z,13Z,16Z,19Z)-docosa-4,7,9,11,13,16,19-heptaenoic[stellaheptaenoic] acid (C₂₂H₃₀O₂).

Alkynyl-functional fatty acids may be selected from:

(9Z)-octadeca-9-en-12-ynoic [crepenynic] acid (C₁₈H₃₀O₂).

Hydroxy-functional fatty acids may be selected from:

12-hydroxy-(9Z)-octadeca-9-enoic [ricinoleic] acid (C₁₈H₃₄O₃).

The cross-linking of the vinyl polymer herein is by autoxidation. In apreferred embodiment, metal ion cross-linking is used in combinationwith the autoxidation mechanism, e.g. by use of coordinative driers asis well known by those skilled in the art. Optionally (although lesspreferred) autoxidation is used in combination with other cross-linkingmechanisms as are known in the art. Other cross-linking mechanisms knownin the art include the reaction of alkoxysilane functional groups,Schiff base cross-linking, epoxy groups reacting with amino, carboxylicacid or mercapto groups, the reaction of amine or mercapto groups withethylenically unsaturated groups such as fumarate and acryloyl groups,the reaction of masked epoxy groups with amino or mercapto groups, thereaction of isothiocyanates with amines, alcohols or hydrazines, thereaction of amines (for example ethylene diamine or multifunctionalamine terminated polyalkylene oxides) with β(beta)-diketo (for exampleacetoacetoxy or acetoamide) groups to form enamines.

The drying process of a coating composition can be divided into stagesfor example the period of time necessary to achieve dust-free and/ortack-free, coatings using the tests described herein.

Preferably the dust free time is less than or equal to 4 hours, morepreferably ≦2 hours and most preferably ≦1 hour.

Preferably the tack-free time is less than or equal to 10 hours, morepreferably ≦6 hours, most preferably ≦4 hours and particularly preferred<3 hours.

A problem often encountered in waterborne autoxidisable vinyl polymersis they have poor hydrolytic stability. This is a particular problemwhen polymer bound carboxylic acid groups are introduced by reactionwith anhydrides, especially when in neutralized form. This problem canbe reduced significantly by reducing the degree of water solubility ofthe autoxidisable resin. However in practice a balance betweenhydrolytic stability and water solubility is required.

The autoxidisable vinyl polymer may contain bound hydrophilicwater-dispersing groups. Suitable hydrophilic groups are well known inthe art, and can be ionic water-dispersing groups or non-ionicwater-dispersing groups. Preferred non-ionic water-dispersing groups arepolyalkylene oxide groups, more preferably polyethylene oxide groups. Asmall segment of the polyethylene oxide group can be replaced by apropylene oxide segment and/or butylene oxide segment, however thepolyethylene oxide group should still contain ethylene oxide (EO) as amajor component. When the water-dispersible group is polyethylene oxide,the preferred EO chain length is ≧4, more preferably ≧8 and mostpreferably ≧15 EO units. Preferably if the autoxidisable vinyl polymercontains polyalkylene oxide groups, the vinyl polymer has a polyalkyleneoxide (optionally EO) content which is at least ≧0%, more preferably≧2%, most preferably ≧3.5% and especially ≧5% and/or is no more than≦50%, more preferably ≦30%, most preferably ≦15% and especially ≦9% byweight of the autoxidisable vinyl polymer. Preferably the polyalkyleneoxide (optionally EO) group has a M_(w) from 175 to 5000 g/mol, morepreferably from 350 to 2200 g/mol, most preferably from 660 to 2200g/mol.

Preferred ionic water-dispersing groups are anionic water-dispersinggroups, especially carboxylic, phosphate, phosphonate or sulphonic acidgroups. Most preferred are carboxylic, phosphate or phosphonate groups.The anionic water-dispersing groups are preferably fully or partially inthe form of a salt. Conversion to the salt form is optionally effectedby neutralisation of the autoxidisable vinyl polymer with a base,preferably during the preparation of the autoxidisable vinyl polymerand/or during the preparation of the composition of the presentinvention. The anionic dispersing groups may in some cases be providedby the use of a monomer having an already neutralised acid group in theautoxidisable vinyl polymer synthesis so that subsequent neutralisationis unnecessary. If anionic water-dispersing groups are used incombination with a non-ionic water-dispersing group, neutralisation maynot be required.

If the anionic water-dispersing groups are neutralised, the base used toneutralise the groups is preferably, an amine or an inorganic base.Suitable amines include tertiary amines, for example triethylamine orN,N-dimethylethanolamine. Suitable inorganic bases include alkalihydroxides and carbonates, for example lithium hydroxide, sodiumhydroxide, or potassium hydroxide. Generally a base is used which givesthe required counter ion desired for the composition. For example,preferred counter ions include tertiary amines or Li⁺, Na⁺, K⁺, NH₄ ⁺and substituted ammonium salts (for example a quaternary ammoniumhydroxide ⁺N(CH₃)₄OH⁻).

Cationic water dispersible groups can also be used, but are lesspreferred. Examples include pyridine groups, imidazole groups and orquaternary ammonium groups which may be neutralised or permanentlyionised. Due to the influence that neutralisation agents have onyellowing, tertiary amines and/or LiOH, NaOH and KOH are especiallypreferred.

The autoxidisable vinyl oligomer when in an aqueous coating compositionpreferably has an acid value (AV, also referred to as an acid number[AN]) from 0 to 28, more preferably from 0 to 18, most preferably from 0to 12 mg KOH/g.

The autoxidisable vinyl oligomer, if carboxylic acid functional,preferably conforms to the following relationship (where ND denotes thedegree to which the acid groups of the oligomer are neutralised):ND×AV≦22,more preferably ≦12 and most preferably ≦8 mg KOH/g.

ND is a dimensionless fraction from 0 to 1 that indicates of the amountof neutralizing agent present in the polymer. For example if 80% of theacid groups on the polymer are neutralised, then the ND value is 0.8. AVis reported in units of mg KOH/g so the product ND×AV has units of mgKOH/g. When the polymer is not neutralised ND is 0 and so is ND×AV isalso 0.

The autoxidisable vinyl polymer preferably has a hydroxyl number whichis at least ≧25, more preferably ≧48 and/or is no more than ≦135, morepreferably ≧110 mg KOH/g.

The aqueous coating composition of the invention preferably has a pHwhich is at least ≧2.0, more preferably ≧3.4 and most preferably ≧4.1and especially ≧4.8 and/or is no more than ≦9.7, more preferably ≦8.4and most preferably ≦7.6.

Preferably the weight average (M_(w)) of the autoxidisable vinyloligomer is at least ≧4000, more preferably ≧5000, most preferably ≧8000and/or is no more than ≦40000 more preferably ≦35000, most preferably≦20000 and especially ≦15000 g/mol. M_(w) is measured by GPC usingpolystyrene standards as described herein.

Preferably the majority of any cross-linking reaction only takes placeafter application of the aqueous coating composition to a substrate, toavoid an excessive molecular weight build up which may lead to anincreased viscosity of the aqueous coating composition on the substratein the early stages of drying.

The molecular weight distribution (MWD) of the vinyl oligomer has aninfluence on the viscosity of the oligomers in the composition and hencean influence on the telegraphing. MWD is conventionally described by apolydispersity index (PDi). PDi is defined as the weight averagemolecular weight (M_(w)) divided by the number average molecular weight(M_(w)/M_(n)) and is dimensionless. It has been found that a lower PDioften results in a lower viscosity and improved flow for an oligomer ofgiven M_(w). The autoxidisable vinyl oligomer may have a PDi which is nomore than ≦8.3 preferably ≦7, more preferably ≦5 and more preferably≦4.5 and/or is at least ≧2.5.

Preferably the weight average particle size of the autoxidisable vinyloligomer dispersed in an aqueous coating composition is at least ≧50 nm,more preferably ≧80 nm, most preferably ≧120 nm and especially ≧150 nm.Preferably at least 80% of the particles have a weight average particlesize ≦1000 nm, more preferably ≦750 nm, most preferably ≦550 nm andespecially ≦400 nm.

Weight average particle size can be measured by any suitable method suchas that described in the test methods herein.

The glass transition temperature (T_(g)) (as measured by DSC of a solidmaterial) of the autoxidisable vinyl oligomer may vary within a widerange and preferably is at least ≧−50° C., more preferably ≧−40° C.,more preferably ≧−25° C. and/or preferably is no more than ≦+15° C.,more preferably ≦+10° C., most preferably ≦+5° C. and especially ≦0° C.Conveniently the T_(g) of the autoxidisable vinyl oligomer may be from−45° C. to −10° C.

If the T_(g) can not be measured by DSC because the first derivative ofthe DSC curve does not show any identifiable maximum, an alternativemethod for determining the T_(g) is by calculating the T_(g) using thefollowing equation that relates viscosity of the pure vinyl oligomer toits T_(g) (which is derived from the Williams-Landau-Ferry [WLF]equation):Ln(η)=27.6−[40.2×(T−T _(g))]/[51.6+(T−T _(g))]where:

-   Ln(η)=Natural logarithm of the viscosity of the pure oligomer    expressed in Pa·s (measured at ambient temperature using a shear    rate from 0.005 and 1 s⁻¹)-   T=23° C.±1° C. (i.e. ambient temperature is used to measure the    viscosity of the pure oligomer) and-   T_(g)=glass temperature expressed in ° C.

Functional groups (such as fatty acid residue or water-dispersinggroups) may be introduced into the autoxidisable vinyl oligomer usingtwo general methods: i) by using monomers carrying the functional groupin the polymerisation process to form autoxidisable oligomer carryingthe functional group; or ii) using monomers bearing selected reactivegroups where monomer is subsequently reacted with a compound carryingthe functional group and also a reactive group of the type which willreact with the selected reactive groups on the monomer to provideattachment of the functional group to the autoxidisable vinyl oligomervia covalent bonding. Thus the autoxidisable vinyl oligomer may beobtained by polymerising autoxidisable vinyl monomers with other vinylmonomers, or, the autoxidisable groups may be attached to the vinyloligomer after radical polymerisation of vinyl monomers to make a vinyloligomer. Preferably the autoxidisable groups are reacted with a vinyloligomer. More preferably the vinyl oligomer comprises epoxy functionalgroups, most preferably glycidyl(meth)acrylate monomers such as GMA.

The autoxidisable vinyl oligomer may be prepared from free radicallypolymerisable ethylenically unsaturated monomer(s), and can containpolymerised units of a wide range of such monomers, especially thosecommonly used to make binders for the coatings industry. By a vinyloligomer herein is meant a homo- or co-polymer derived from additionpolymerisation, using a free radical initiated process which may becarried out in an aqueous or non-aqueous medium, of one or moreethylenically unsaturated monomers. Therefore by a vinyl monomer ismeant an ethylenically unsaturated monomer.

Examples of vinyl monomers which may be used to form a vinyl oligomerinclude but are not limited to: 1,3-butadiene, isoprene, styrene,α-methyl styrene, divinyl benzene, acrylonitrile, methacrylonitrile,vinyl ethers, vinyl esters such as vinyl acetate, vinyl propionate,vinyl laurate, and vinyl esters of versatic acid such as VeoVa 9 andVeoVa 10 (VeoVa is a trademark of Shell), heterocyclic vinyl compounds,alkyl esters of mono-olefinically unsaturated dicarboxylic acids (suchas di-n-butyl maleate and di-n-butyl fumarate) and, in particular,esters of acrylic acid and methacrylic acid of Formula ICH₂═CR¹—COOR²  Formula Iwhere R¹ is H or methyl and R² is optionally substituted C₁₋₂₀ alkyl(preferably C₁₋₈alkyl) or optionally substituted C₃₋₂₀ cycloalkyl(preferably C₃₋₈ cycloalkyl), examples of which are methyl acrylate,methyl methacrylate, ethyl acrylate, ethyl methacrylate, n-butylacrylate, n-butyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexylmethacrylate, isopropyl acrylate, isopropyl methacrylate, n-propylacrylate, n-propyl methacrylate, and hydroxyalkyl(meth)acrylates such ashydroxyethyl acrylate, hydroxyethyl methacrylate, 2-hydroxypropylmethacrylate, 2-hydroxypropyl acrylate, 4-hydroxybutyl acrylate,4-hydroxybutyl methacrylate and their modified analogues like Tone M-100(Tone is a trademark of Union Carbide Corporation).

Ethylenically unsaturated monocarboxylic, sulphonic and/or dicarboxylicacids, such as acrylic acid, methacrylic acid, β-carboxy ethyl acrylate,fumaric acid and/or itaconic acid may be used. Ethylenically unsaturatedmonomers such as (meth)acrylamide and/ormethoxypolyethyleneoxide(meth)acrylate may also be used.

The vinyl monomer may optionally contain functional groups to contributeto the cross-linking of the vinyl polymer(s) in the coating. Examples ofsuch groups include: maleic, epoxy, fumaric, acetoacetoxy,β(beta)-diketone, acryloyl, methacryloyl, styrenic, (meth)allyl groups,mercapto groups, keto or aldehyde groups (such as methyl vinyl ketone[MEK], diacetone acrylamide and (meth)acrolein).

Preferred vinyl polymers have a backbone made from a monomer systemcomprising at least 40% of one or more monomers of Formula I by weightof the polymer. Such a preferred backbone for the vinyl polymer isdefined herein as an (meth)acrylic polymer. A particularly preferredautoxidisable vinyl polymer is an autoxidisable acrylic polymer (i.e.based predominantly on at least one ester of acrylic and/or methacrylicacid). More preferably, the monomer system for the vinyl backbonecomprises at least 50%, most preferably at least 60% of such monomers byweight of polymer. The other monomer(s) in such acrylic autoxidisablevinyl polymers (where used) may include one or more of the other vinylmonomers mentioned above, and/or may include monomer(s) different tosuch other monomers.

Particularly preferred monomers include butyl acrylate (all isomers),butyl methacrylate (all isomers), methyl methacrylate, ethyl hexylmethacrylate, esters of (meth)acrylic acid, acrylonitrile, vinyl acetateand styrene.

Preferably the vinyl polymer contains less than 40% styrene, morepreferably less then 20%, most preferably less than 12% and especiallyless than 5% by weight of polymer.

Preferably the vinyl polymer prepared in step I (before fatty acidfunctionalisation) is substantially free of chlorine containingmonomers. Substantially free means such monomers are in an amount ≦1%,more preferably ≦0.5% and especially 0% by weight of the vinyl polymerprepared in step I.

Alternatively vinyl functional monomers with an autoxidisable moiety canbe used, like the reaction product of GMA and fatty acid or the monomerSerAD FX522 available commercially from Servo Condea under that tradename.

In a preferred embodiment first a vinyl oligomer is prepared, which issubsequently reacted to obtain an autoxidisable vinyl oligomer of theinvention.

Monomers “G” which are useful for reacting the fatty acid onto the vinyloligomer to give fatty acid residues includehydroxylalkyl(meth)acrylates, such as hydroxyethyl(meth)acrylate,hydroxypropyl(meth)acrylate and ToneM-100 and epoxy functional vinylmonomers like glycidyl(meth)acrylate (GMA) or 3,4-epoxy-cyclohexylmethyl-acrylate.

In a preferred embodiment 30% to 70% of monomer G (by weight of thetotal monomers) is used, before functionalisation, to obtain anautoxidisable vinyl oligomer of the invention. Preferably the vinyloligomer comprising monomer G is then reacted with fatty acid, wheretypically between 0.4 and 1.0 equivalent of fatty acid is reacted withthe graftable groups present on the vinyl oligomer. For this purpose, itis considered that a hydroxyl graftable group can react once with afatty acid, whereas a epoxy graftable group can react twice, due to theadditionally formed hydroxyl group on ring opening. A particularlypreferred monomer G is GMA.

The autoxidisable vinyl oligomer is preferably prepared by free radicalpolymerisation, although in some circumstances anionic polymerisationmay be utilised. The free radical polymerisation can be performed bytechniques known in the art, for example as emulsion polymerisation,solution polymerisation, suspension polymerisation or bulkpolymerisation.

The autoxidisable vinyl oligomer is preferably prepared in one or moresolvents before being dispersed in water.

The autoxidisable vinyl oligomer is preferably made in a non-continuousprocess to allow for improved control during polymerisation.

Preferably less then 10% and more preferred less then 5% of theautoxidisable vinyl oligomer solids (by weight of solids) should consistof oligomeric vinyl material which is covalently bound to a fatty acid,whereby the covalent bond is generated through a grafting reaction of apropagating vinyl radical onto the unsaturated fatty acid.

In the latter case the fatty acid can either be a free unsaturated fattyacid or an unsaturated fatty which is part of a polymeric structure.

Most preferably there is no grafting of vinyl monomers to the fatty acidat all.

A free-radical polymerisation of vinyl monomer(s) to form acrosslinkable vinyl autoxidisable vinyl oligomer or precursor vinylautoxidisable vinyl oligomer will require the use of afree-radical-yielding initiator(s) to initiate the vinyl polymerisation.Suitable free-radical-yielding initiators include inorganic peroxidessuch as K, Na or ammonium persulphate, hydrogen peroxide, alkylhydroperoxides such as t-butyl hydroperoxide and cumene hydroperoxide;dialkyl peroxides such as di-t-butyl peroxide and the like; mixtures mayalso be used. The peroxy compounds are in some cases advantageously usedin combination with suitable reducing agents (redox systems) such as Naor K pyrosulphite or bisulphite, and iso-ascorbic acid.

It may be desirable to control the molecular weight by addition of achain transfer agent to the free radical polymerisation process.Conventional chain transfer agents may be utilised and includemercaptans, sulphides, disulphides and halocarbons. In particularhowever the technique known as catalytic chain transfer polymerisation(CCTP) may be used to provide low molecular weights. In this case a freeradical polymerisation is carried out using a free radical forminginitiator and a catalytic amount of a selected transition metal complexacting as a catalytic chain transfer agent (CCTA), and in particular aselected cobalt chelate complex. Such a technique has been described forexample in N. S. Enikolopyan et al, J. Polym. Chem. Ed., Vol 19, 879(1981), U.S. Pat. No. 4,526,945, U.S. Pat. No. 4,680,354, EP-A-0196783,EP-A-0199436, EP-A-0788518 and WO-A-87/03605.

The use of catalytic chain transfer agents provide four importantbenefits:

-   -   a) very low concentrations of catalytic chain transfer agent        (typically 1 to 1000 ppm by weight of vinyl monomer used) are        required to attain the preferred low molecular weight oligomer        and do not have the odour often associated with conventional        chain transfer agents;    -   b) a vinyl autoxidisable vinyl oligomer prepared by CCTP        contains a terminal unsaturated group on many, if not every        vinyl oligomer molecule. This terminal unsaturation can        participate in autoxidation reactions for example in fatty acid        crosslinking systems. Thus the crosslinkable vinyl autoxidisable        vinyl oligomer of the present invention could have autoxidisable        crosslinker groups comprising the unsaturated groups from fatty        acids as well as terminal unsaturated groups resulting from        CCTP.    -   c) CCTP allows the preparation of a vinyl autoxidisable vinyl        oligomer which has a narrower PDi than is achievable by the use        of conventional chain transfer agents for low Mw autoxidisable        oligomer.    -   d) Especially when epoxy functional monomers are used, CCTP has        the benefit compared to e.g. chain transfer agents with        mercaptan groups, that the CCTA does not react with the epoxy        groups.

The solids content of the aqueous coating composition of the inventionis at least preferably ≧45% and more preferably ≧49% and/or is no morethan preferably ≦72%, more preferably ≦65% and most preferably ≦63% byweight of the composition.

The autoxidisable vinyl oligomer may be dispersed in water usingtechniques well known in the art. The crosslinkable autoxidisable vinyloligomer normally requires the use of an external surfactant when beingdispersed into water. Surfactants and or high shear can be utilised inorder to assist in the dispersion of the autoxidisable vinyl oligomer inwater. Suitable surfactants include but are not limited to conventionalanionic, cationic and/or non-ionic surfactants such as Na, K and NH₄salts of dialkylsulphosuccinates, Na, K and NH₄ salts of sulphated oils,Na, K and NH₄ salts of alkyl sulphonic acids, Na, K and NH₄ alkylsulphates, alkali metal salts of sulphonic acids; fatty alcohols,ethoxylated fatty acids and/or fatty amides, and Na, K and NH₄ salts offatty acids such as Na stearate and Na oleate. Other anionic surfactantsinclude alkyl or (alk)aryl groups linked to sulphonic acid groups,sulphuric acid half ester groups (linked in turn to polyglycol ethergroups), phosphonic acid groups, phosphoric acid analogues andphosphates or carboxylic acid groups. Cationic surfactants include alkylor (alk)aryl groups linked to quaternary ammonium salt groups. Non-ionicsurfactants include polyglycol ether compounds and polyethylene oxidecompounds. The surfactants may also be polymeric surfactants which arealso described as wetting agents.

The amount of total surfactants used in aqueous compositions of theinvention is preferably at least ≧0.1%, more preferably ≧1%, mostpreferably ≧3% and/or is preferably no more than ≦11%, more preferably≦9% and most preferably ≦7% by weight of the autoxidisable vinyloligomer. Preferably a mixture of anionic and non-ionic surfactants areused.

If the aqueous composition comprising anionic surfactant, the anionicsurfactant may comprise ethylene oxide (EO) groups in an amount which ispreferably no more than ≦90%, more preferably ≦70%; most preferably ≦55%and/or is preferably at least ≧10% and/or ≧20% EO groups by weight ofthe surfactant. Preferred anionic surfactants comprise sulphate,sulphonate, phosphate and/or phosphonate groups.

The aqueous composition may comprise non-ionic surfactant in an amountof preferably at least ≧0.1%, more preferably ≧0.5%, still morepreferably ≧1% and most preferably ≧1.5% and/or preferably no more than≦12%, more preferably ≦9%, still more preferably ≦5% and most preferably≦3.5% by weight of vinyl oligomer solids.

Optionally to reduce the effect of cissing the composition comprisesionic surfactant in an amount of at least preferably ≧0.1%, morepreferably ≧0.5%, still more preferably ≧1% and most preferably ≧1.5%and/or no more than preferably ≦12%, more preferably ≦9%, mostpreferably ≦5% by weight of vinyl polymer solids.

Dispersants (such as dispersing compounds and/or dispersing resin) whichpreferably are autoxidisable (such as W-3000 available from Perstorp oras described in EP1870442) could also be employed instead of or combinedwith more conventional surfactants. Optionally where used the dispersant(such as a dispersing resin) is present in amount of at least preferably≧0.1%, more preferably ≧3% and most preferably ≧5% and/or no more thanpreferably ≦30%, more preferably ≦20% and most preferably ≦12% by weightof solid resin.

The aqueous coating composition of the invention is particularly usefulas or for providing the principle component of coating formulations(i.e. composition intended for application to a substrate withoutfurther treatment or additions thereto) such as protective or decorativecoating compositions (for example paint, lacquer or varnish) wherein aninitially prepared composition optionally may be further diluted withwater and/or organic solvents, and/or combined with further ingredientsor may be in more concentrated form by optional evaporation of waterand/or organic components of the liquid medium of an initially preparedcomposition.

An organic solvent may optionally be added before, during and/or afterthe polymerisation process for making the autoxidisable vinyl oligomerto control the viscosity. Examples of solvents include water-misciblesolvents such as propylene glycol based solvents, especially propyleneglycol mono methyl ether and dipropylene glycol mono methyl ether andglycol ethers such as butyldiglycol. Optionally no organic solvents areadded.

A co-solvent, as is well known in the coating art, is an organic solventemployed in an aqueous composition to ameliorate the dryingcharacteristics thereof, and in particular to lower its minimum filmforming temperature. The co-solvent may be solvent incorporated or usedduring preparation of the autoxidisable vinyl oligomer or may have beenadded during formulation of the aqueous composition.

The aqueous composition of the invention may have a co-solvent contentin an amount of at least preferably ≧2%, more preferably ≧3.5%, and mostpreferably ≧5% and/or no more than preferably ≦18%, more preferably ≦15%and most preferably ≦9% by weight of oligomer solids. Most preferablysubstantially no co-solvent is used as this gives improved storagestability and a better ecological profile.

An advantage of the current invention is that co-solvent can, as isoften required for environmental and safety reasons, be present at avery low concentrations because of the plasticising nature of theautoxidisable oligomer.

Preferably the use of a nitrogen containing solvent is less desired forreasons of toxicity profile, yellowing and odour.

In general, aromatic or heterocyclic nitrogen-containing ligands oraromatic and aliphatic primary and secondary (di)amines were found toprolong the drying time to a considerable extent (as reported inCoordination Chemistry Reviews 249 (2005) 1709-1728). An exampleincludes heterocyclic nitrogen-containing solvents such asN-methylpyrrolidone (NMP) and N-ethylpyrrolidone.

Preferably the aqueous coating composition comprises NMP in an amount ofno more than ≦13%, more preferably ≦10%, most preferably ≦5% andespecially ≦0.5% by weight of oligomer solids.

Preferably the aqueous coating composition comprises only a small amountof nitrogen containing molecules with an evaporation rate ≦0.1, morepreferably ≦0.05 (as calculated below), the molecules being aromatic,heterocyclic or aliphatic primary and secondary di-amines where theweight % of nitrogen is ≧5% and more preferably ≧10%.

Preferably such nitrogen containing molecules are present in the aqueouscoating composition in an amount ≦13%, more preferably ≦8%, mostpreferably ≦5% and especially ≦0.5% by weight of oligomer solids.

Values for evaporation rates were published by Texaco Chemical Companyin a bulletin Solvent Data; Solvent Properties (1990). These values arerelative to the evaporation rate of n-butyl acetate for which theevaporation rate is defined as 1.00. Determination of evaporation ratesof solvents not listed in this bulletin is as described in ASTM D3539.Co-solvents with low evaporation rates give undesired effects in thefinal coatings resulting in slow hardness development acting as aplasticizer.

It is preferred to have <16% by weight of oligomer solids of aco-solvent with an evaporation rate between 0.05 and 0.005.

Preferably when the aqueous composition is formulated as paint, thecomposition comprises 2% to 10%, more preferably 3% to 9% of solvent byweight of the total paint composition. Preferably at least 50%, morepreferably ≧80%, most preferably ≧95% by weight of the total solvent aresolvent(s) having an evaporation rate (as defined herein) higher than0.012, more preferably from 0.018 to 0.25, most preferably lower than0.21.

The aqueous coating composition of the invention may be applied to avariety of substrates including wood, board, metals, stone, concrete,glass, cloth, leather, paper, plastics, foam and the like, by anyconventional method including brushing, dipping, flow coating, spraying,and the like. They are, however, particularly useful for providingcoatings on wood and board substrates. The aqueous carrier medium isremoved by natural drying or accelerated drying (by applying heat) toform a coating. Accordingly in a further embodiment of the inventionthere is provided a coating obtainable from an aqueous coatingcomposition of the present invention.

The aqueous coating composition of the invention may contain otherconventional ingredients including pigments, dyes, emulsifiers,surfactants, plasticisers, thickeners, heat stabilisers, levellingagents, anti-cratering agents, fillers, sedimentation inhibitors, UVabsorbers, antioxidants, dispersants, reactive diluents, waxes,neutralising agents, adhesion promoters, defoamers, co-solvents, wettingagents and the like introduced at any stage of the production process orsubsequently. It is possible to include fire retardants like antimonyoxide in the dispersions to enhance the fire retardant properties.

Preferred reactive diluents (which may or may not be the autoxidisable)may also have one or more of the following properties: M_(n)>1000 g/mol,more preferably >1500 g/mol and most preferably >2000 g/mol; M_(n)<5000g/mol, more preferably <4000 g/mol and especially <3500 g/mol; and/oroptionally (e.g. where the reactive diluent is autoxidisable) from 60 to90 wt %, more preferably 75 to 90%, most preferably 80 to 90% of fattyacid residues with an iodine value from 50 to 175, more preferably from80 to 150 g I₂/100 g by weight of sample.

In particular, the aqueous coating compositions of the invention andformulations containing them advantageously include at least a driersalt. Drier salts are well known to the art for further improving curingin unsaturated film-forming substances. Generally speaking, drier saltsare metallic soaps, that is salts of metals and long chain carboxylicacids. It is thought that the metallic ions effect the curing action inthe film coating and the fatty acid components confer compatibility inthe coating medium. Examples of drier metals are cobalt, manganese,zirconium, lead, neodymium, lanthanum and calcium. The level of driersalt(s) in the composition is typically that to provide an amount ofmetal within the range of from 0.01 to 0.5% by weight based on theweight of autoxidisable oligomer.

Drier salts are conventionally supplied as solutions in solvents for usein solvent-borne alkyd systems. They may, however, be used quitesatisfactorily in aqueous coating compositions since they can normallybe dispersed in such systems fairly easily. The drier salt(s) may beincorporated into the aqueous coating composition at any convenientstage. For example the drier salt(s) may be added prior to dispersioninto water. Drier accelerators may be added to the drier salts. Suitabledrier accelerators include 2,2′-bipyridyl and 1,10-phenanthroline.

In an embodiment of the present invention there is provided an aqueousautoxidisable coating composition with reduced telegraphing as definedherein comprising an autoxidisable vinyl oligomer obtained by a processcomprising steps:

-   -   1) polymerising ethylenically unsaturated vinyl monomers        comprising:        -   i) 30% to 70% of at least one monomer G selected from            hydroxylalkyl(meth)acrylates and epoxy functional vinyl            monomers;        -   ii) 30% to 70% of at least one other ethylenically            unsaturated vinyl monomer; and        -   iii) <1% of chlorine containing monomers;        -   where the percentages are by weight of total monomers;    -   II) reacting the oligomer obtained in step I) with fatty acids        having an average iodine value in the range of 80 to 180 g        I₂/100 g fatty acid;        -   wherein the autoxidisable vinyl oligomer comprises by weight            of oligomer: 35% to 62% of polymeric backbone; and 38% to            65% of fatty acid residue; and        -   where the autoxidisable vinyl oligomer has:        -   i) a T_(g) from −50° C. to 15° C.;        -   ii) a M_(w) from 6500 to 25000 g/mol; and        -   iii) a PDi from 2 to 8;        -   said composition having        -   a) a co-solvent content 15% by weight of solids;        -   b) a N-methylpyrrolidone content 3% by weight of solids;        -   c) heterocyclic amine containing solvent content of 0 wt %            by weight of solids;        -   d) a solids content 38% by weight of the composition;        -   e) a pH from 4.1 to 8.4.        -   and        -   where said composition when in the form of a film has a            telegraphing value (as defined herein) or less than 10 gloss            units and optionally the film has a tack free time <6 hours.

In an another embodiment of the invention there is provided an aqueousemulsion coating composition with a telegraphing value (as definedherein) of less than 10 gloss units, said composition comprising:

-   -   i) 38% to 65% of the autoxidisable vinyl oligomer described        herein;    -   ii) 0 to 20%, more preferably 0 to 15%, most preferably 0 to 10%        and especially 0 to 5% of co-solvent; and    -   iii) 15% to 58% of water; where all percentages are by weight of        the composition and i)+ii)+iii)=100%.

In another embodiment of the invention there is provided an aqueousemulsion coating composition with a telegraphing value (as definedherein) of less than 10 gloss units said composition comprising:

-   -   i) 20% to 45%, preferably 25 to 40%, of TiO₂;    -   ii) 20% to 45%, preferably 25 to 40%, of the autoxidisable vinyl        oligomer as described herein;    -   iii) 0 to 10%, preferably 0 to 5%, of co-solvent;    -   iv) 0.1% to 3% of thickener;    -   v) 0 to 5% of dispersing agent; and    -   vi) 25% to 60% water;    -   where all percentages are by weight of the composition and        i)+ii)+iii)+iv)+v)=100%.

If desired the aqueous dispersion of the invention can be used incombination with other polymer dispersions or solutions.

Preferably such other dispersions or solutions comprise less than orequal to 35%, more preferably ≦20%, most preferably ≦10% and especiallypreferably ≦4% by weight of the total autoxidisable vinyl oligomer.

Preferably the aqueous coating composition when coated onto a substrateis water resistant, in the tests as described herein, for 30 minutes,more preferably for 1 hour and most preferably for 3 hours.

Preferably the aqueous coating composition when coated onto a substrateis block resistant in the tests as described herein at ambienttemperature with a rating of 3 or more preferably at 52° C. with arating of 3 or more.

Preferably the aqueous coating composition is a one component system,meaning that preferably no additional crosslinking agents, likepolyaziridines, polycarbodiimides or polyisocyanates or melamines areadded to the aqueous coating composition, prior to applying thecomposition to a substrate.

Preferably the aqueous coating composition is free from photoinitiatorsand is cured without the use of radiation curing equipment.

A further aspect of the invention provides a coating obtained and/orobtainable by a coating composition of the invention and having atelegraphing value (as defined herein) of less than 10 gloss units.

Another aspect of the invention provides a substrate coated with acoating of the invention.

A still other aspect of the invention provides a method of coating asubstrate comprising the steps of i) applying a coating composition ofthe invention to the substrate; ii) drying the substrate to form acoating thereon; where the coating has a telegraphing value (as definedherein) of less than 10 gloss units.

Yet another aspect of the invention provides use of an autoxidisablevinyl polymer and/or a coating composition of the invention for thepurpose of obtaining coatings having a telegraphing value (as definedherein) of less than 10 gloss units.

A still yet other aspect of the invention provides a method ofmanufacture of an autoxidisable vinyl polymer and/or a coatingcomposition of the invention for the purpose of obtaining coatingshaving a telegraphing value (as defined herein) of less than 10 glossunits.

Many other variations embodiments of the invention will be apparent tothose skilled in the art and such variations are contemplated within thebroad scope of the present invention. Further aspects of the inventionand preferred features thereof are given in the claims herein.

The present invention is now illustrated by reference to the followingnon-limiting examples. Unless otherwise specified, all parts,percentages and ratios are on a weight basis. The prefix C before anexample denotes that it is comparative. The term “working” means thatthe example is according to the invention. The term “non-working” meansthat it is not according to the invention (i.e. comparative).

Various registered trademarks, other designations and/or abbreviationsare used herein to denote some of ingredients used to prepare polymersand compositions of the invention. These are identified below bychemical name and/or trade-name and optionally their manufacturer orsupplier from whom they are available commercially. However where achemical name and/or supplier of a material described herein is notgiven it may easily be found for example in reference literature wellknown to those skilled in the art: such as: ‘McCutcheon's Emulsifiersand Detergents’, Rock Road, Glen Rock, N.J. 07452-1700, USA, 1997 and/orHawley's Condensed Chemical Dictionary (14th Edition) by Lewis, RichardJ., Sr.; John Wiley & Sons.

‘AIBN’ denotes azobisisobutyronitrile;

‘Additol VXW4940’ denotes the drying pigment commercially available fromElementis under this trade name;

‘Atlas G5000’ denotes the nonionic polyalkylene glycol ether availablecommercially from Uniqema under this trade designation;

‘BA’ denotes n-butyl acrylate

‘3,5-BHT’ denotes 3,5-di-tert-butyl-4-methylphenol (also known as butylhydroxy toluene);

‘BMA’ denotes n-butylmethacrylate;

‘CoF’ denotes the catalyst Co II (bis 4,4′-dimethylbenzildioxime)diborondifluoride, as described in EP1742973-A, US2007219328 andWO2005105855;

‘Dehydran 1293; denotes a solution of a special modified polydimethylsiloxane defoamer that is commercially available from Cognis under thistrade name;

‘Disperbyk 190” denotes that a solution of a high molecular weight blockcopolymer with pigment affinic groups that is a dispersing additive forpigments that is commercially available from BYK Chemie under this tradename;

‘Dow PnP’ denotes that propylene glycol n-propyl ether mixturecommercially available from Dow Chemicals under the trade name DowanolPnP;

‘dtAP’ denotes di-tert-amylperoxide

‘dtBP’ denotes di-tert-butylperoxide

‘FES77’ denotes the dispersant which is a sodium salt of a fatty alcoholgycol ether sulphate and is available commercially from Cognis under thetrade name Disponil FES 77;

‘FES993’ denotes the dispersant which is a sodium salt of a fattyalcohol gycol ether sulphate and is available commercially from Cognisunder the trade name Disponil FES 993 IS;

‘GMA’ denotes glycidyl methacrylate;

‘HHPA’ denotes hexahydro phtalic anhydride;

‘Kronos 2190’ denotes a titantium dioxide pigment commercially availablefrom Kronos under this trade name;

‘MMA’ denotes methyl methacrylate;

‘MSA’denotes methane sulphonic acid

‘FAA’ denotes a conventional polyacrylic acid with weight averagemolecular weight (Mw) of from 200-250 KDalton which has been prepared bythe applicant;

‘PVC’ denotes polyvinyl chloride

‘Sefose’ denotes a soyate made from partially hydrogenated soybean oilwhich is commercially available from P&G Chemicals under the trade nameSefose 1618SC,

‘Sun-FA’ denotes sunflower fatty acid;

‘tBP’ denotes tert-butyl peroxide

‘tBPD’ denotes t-butyl peroxybenzoate

‘TEA’ denotes triethyl amine;

‘THF’ denotes tetrahydrofuran; and

‘TRAP’ denotes triphenyl ethyl phosphonium bromide.

Test Methods:

Standard Conditions

As used herein, unless the context indicates otherwise, standardconditions (e.g. for drying a film) means a relative humidity of 50%±5%,ambient temperature (23° C.±2°) and an air flow of 0.1 m/s.

Particle Size

The particle sizes given herein are the size of a weight averagedparticle and are quoted as a linear dimension which is a particlediameter as the particles can be considered to be essentially spherical.Weight average particle size may be measured using Scanning/TransmissionElectron Microscope and Photon Correlation Spectroscopy.

Iodine Number

The iodine value (also referred to herein as iodine number) is a measureof the amount of ethylenic unsaturated double bonds in a sample andincreases with a greater degree of unsaturation. Iodine value may bedefined according to DIN 53241-1 as the quotient of that mass m_(I) ofiodine which is added on to the olefinic double bonds, withdecolourisation, of a sample to be analysed and the mass m_(B) of thissample (mass of the solid in the sample in the case of solutions ordispersions). Iodine values may be quoted either in units of centigramsof iodine per gram of sample (cg I₂/g) or in units of grams of iodineper 100 gram of sample (g I₂/100 g). Standard methods for analysis maybe used such as for example ASTM D5768-02 (2006) and DIN 53241. Onecommon method (and that used to measure the iodine values given herein)is the Wjjs method in which iodine absorption is determined by titratingunreact reagent with sodium thiosulfate and the iodine value is thencalculated as follows:

${{Iodine}\mspace{14mu}{value}} = \frac{(12.69) \times ( {{ml}\mspace{14mu}{of}\mspace{14mu}{thiosulfate}} ) \times ({normality})}{{mass}\mspace{14mu}{of}\mspace{14mu}{sample}\mspace{14mu}(g)}$Telegraphing

Two types of PVC substrates are used to determine the degree oftelegraphing of an unpigmented coating comprising the autoxidisableresin:

The first PVC type is the 2 mm thick rough PVC substrate with a welldefined and uniform rough surface that is available commercially fromVink Kunststoffen B.V (Didam, Holland) under the trade name Vikuporwhite PVC film type JD11. An area of 1.9×2.5 mm of the substrate surfaceis analysed with a Wyko optical profilometer NT1100 at a magnificationof 2.5 to give R_(z)=25 μm±5 μm. R_(z) denotes the ‘ten-point height’,which is the average of the five greatest peak-to-valley separations inthe scanned area, and is regarded as a general value for surfaceroughness. The second PVC type is a 3 mm thick smooth PVC substrate witha well defined smooth surface that is also available commercially fromVink Kunststoffen under the trade name Vikunyl white PVC film glossytype 206221. R_(z)=1 μm±0.25 μm. (measured as for rough PVC).

The unpigmented coating comprising (optionally comprising flow andwetting agents and thickeners if needed) is cast on both PVC substrates(rough and smooth) and a smooth and defect free film is obtained,resulting in a theoretical dry film thickness between 52 μm±6 μm. Thefilm is dried under standard conditions for 24 hours and the gloss ismeasured at a 20° angle. This gloss measurement is repeated after 4days, 7 days and 14 days. The difference in gloss readings between thefilms on rough and smooth PVC is a quantitative measure of the extent towhich the rough surface of the PVC is telegraphed to the surface of thedried coating. The smaller the difference in these gloss values, thesmaller the degree of telegraphing and the better the coating hides thesubstrate roughness.

Also the absolute value for gloss reading on rough PVC should notdecrease significantly in time so that the reduced telegraphing ismaintained.

Drying Time:

To test the dust-free and tack-free drying times of the compositionsprepared in the Examples as described below, the compositions areformulated and applied to a glass plate at a wet film thickness of 80μm. Tests for drying times are performed at regular time intervals understandard conditions.

Dust-Free Time:

The dust-free time (DFT) is determined by dropping a piece of cottonwool (about 1 cm³ i.e. 0.1 g) on to the drying film from a distance of25 cm. If the piece of cotton wool can immediately be blown from thesubstrate by a person without leaving any wool or marks in or on thefilm, the film is considered to be dust-free.

Tack-Free Time:

The tack-free time (TFT) is determined by placing a piece of cotton wool(about 1 cm³, 0.1 g) on the drying film and placing a weight of 1 kgonto the piece of cotton wool (for 10 seconds). If the piece of cottonwool can be removed from the substrate by hand without leaving any woolor marks in or on the film, the film is considered to be tack-free.

Blocking Test

A 100 μm thick wet film is cast on a Leneta chart and dried for 24 hoursunder standard conditions. Resistance to blocking is determined using ablock tester, where pairs of the coated test charts are placed with thefilm coatings face to face and left at ambient temperature for 4 hoursor left at 52° C. for 2 hours with a pressure of 250 g/cm². Aftercooling to ambient temperature (if applicable), the test charts arepeeled apart and the degree of block resistance is assessed, rangingfrom 0 (very poor blocking resistance) to 5 (excellent blockingresistance). When the test charts can be peeled apart using minor forcewithout damaging the surface of the film, blocking is assessed as 3.

Measurement of Film Yellowing:

The yellowing of a coating exposed to daylight or darkness for aspecified time period is determined using a Dr Lange Spectropen. Theequipment is calibrated to the defined values of the calibration plateand then the b-value is measured according to the CIE L, a, b method.The dark-yellowing is defined as the increase in the yellowness (Δb) ofthe coating during storage at 52° C., in the dark for 21 days.

Molecular Weight Determination:

Gel permeation chromatography (GPC) analysis for the determination ofpolymer molecular weights are performed on an Alliance Waters 2695 GPCwith three consecutive PL-gel columns (type Mixed-B, 1/d=300/7.5 mm)using tetrahydrofuran (THF, HPLC grade, stabilized with3,5-di-tert-butyl-4-hydroxytoluene [BHT], preferably with 1.0 vol. %acetic acid) as the eluent at 1 cm³/min and using an Alliance Waters2410 refractive index detector. A set of polystyrene standards (analysedaccording to DIN 55672) are used to calibrate the GPC. Samplescorresponding to about 16 mg of solid material are dissolved in 8 cm³ ofTHF. The samples are regularly shaken and dissolved for at least 24hours for complete “uncoiling” and placed on the auto-sampling unit ofthe Alliance Waters 2695. The injection volume is 150 μL and thetemperature of the column oven is established at 35° C.

Glass Transition Temperature (T_(G))

The T_(g) is measured by DSC using the TA Instruments DSC Q1000 withstandard TA Instruments alumina cups of 50 μl. The flow rate is 50ml/min of nitrogen and the sample is loaded at ambient temperature. Thesample is cooled until it reached an equilibrium temperature of −90° C.and then heated at a rate of 10° C./min to 100° C., kept for 5 minutesat 100° C., cooled to −90° C. at a rate of 20° C./min, kept for 5minutes at −90° C. and subsequently heated at a rate of 10° C./min to100° C.

The T_(g) values in the Examples and Tables herein are the midpoint asmeasured by DSC as described above.

Water Resistance:

A 100 μm thick wet film is cast on a Leneta chart and dried for 24 hoursunder standard conditions. Then three drops of water are placed on thefilm and one drop of water is removed after 30 minutes, one after 1 hourand one after 3 hours. The water resistance is assessed immediatelyafter removal of the water and then after 24 hours. The rating for waterresistance is from: 0=very poor, dissolved; 3=acceptable; 5=excellent,no damage of the coating.

Gloss Measurement Method:

Gloss measurements are carried out on a BYK Gardner micro-TRI-gloss20-60-85 gloss meter in accordance with ASTM D523-89.

The examples herein are prepared by the following common method modifiedas indicated in the tables with reference to each of the alphanumericlabels given below.

Common Method

Step (A1) Preparing an Epoxy Functional Vinyl Polymer (Alternative 1)

In one alternative (A1) of step a round bottom reaction vessel (VOL)equipped with a stirrer, baffle and cooler, is loaded with water (a),Na₂SO₄ (b) and PAA (c) in a nitrogen atmosphere. The mixture isneutralized with NaOH until the pH is >8 and the mixture temperature isbrought to 60° C. A homogeneous mixture of MMA (d), BMA (e), GMA (f),AlBN (g) and CoF (h) is transferred to the reactor and the reactiontemperature is brought to 80° C. After time t1 a mixture of FES993 (i)and water (j) is added to the reactor. After time t2 the temperature israised to 85° C. and is held there for 60 minutes. The reaction vesselis then cooled to ambient temperature and polymer beads are obtainedthat are washed and dried for use in the next step (B).

The polymer obtainable in this step (A1) is characterised as follows:

-   -   M_(n)=k, M_(w)=I, PDi=m, T_(g)=n.        Step (A2) Preparing an Epoxy Functional Vinyl Polymer        (Alternative 2)

A round bottom, optionally high pressure where specified herein, reactor(VOL′), equipped with stirrer and cooler, is loaded under nitrogen witha solvent (SOL1, a′) and heated to T′1. A homogeneous mixture of styrene(b′), GMA (c′), BA (dd′), BMA (d′), d-BP (e′) and t-BPB (f′) is fed tothe reactor using a pump over time t′1 at pressure (g′).

Optionally after the ingredients have been added to the reactor the pumpis rinsed with more solvent (SOL1, h′), and the reactor is then heatedto T′2 for time t′2, cooled to T′3 and then dtAP (i′) is added in smallportions over time t′3.

The mixture is held at 140° C. for time t′4 and then the reactor iscooled to ambient temperature. Optionally further solvent is added(SOL1, j′)

The polymer obtainable in this step (A2) is characterised as follows:Solid content=k′, M_(n)=M_(w)=m′, PDi=n′

Step (B) Preparing an Aqueous Autoxidisable Vinyl Polymer

An amount (p) of vinyl polymer prepared as described in the commonmethod step (A1 or A2) above is dissolved in a solvent (SOL2, q). SunFA(r) and TRAP (s) are added to the resulting solution to form a mixturewhich is heated at 120° C. under nitrogen. The reaction is continueduntil an acid value (t) is reached.

SOL2 is removed by distillation under reduced pressure and the polymerobtained is characterised as follows:

-   -   M_(n)=u, M_(w)=v, PDi=w, T_(g)=x.        Step (C) Dispersing Vinyl Polymer Obtainable from Step (B)

To an amount (y) of a polymer prepared as described in the common methodstep (B) is added Atlas G5000 (z), ALES (aa) and Ingredient) (IGD1, ab).Then water (ac) is added slowly to form a dispersion which is stirredfor 30 minutes before being stored under nitrogen. The dispersion ischaracterised as follows:

solids content=ad, pH=pH2, ND×AV=ae

All the examples were prepared as described in the common methods withreference to the data in the Tables (as shown below). In the Tables NMindicates a parameter is not measured and NA that that parameter is notapplicable to that example.

The properties of coatings made from the examples and pigment pastes PP1prepared by mixing the ingredients as indicated in Table 7 are alsotested and the results given in Table 8 below.

TABLE 1 Common method Step A - Alternative 1 - Process conditions ItemVessel Rtn. Add. size Water Na₂SO₄ PAA MMA BMA GMA AIBN CoF time FES993water time Units liters grams grams grams grams grams grams grams gramsmins grams grams mins Label Ex VOL a b c d e f g h t1 l j t2 C1a 2 867.81.59 0.79 381.59 0 254.39 4.77 0.01 45 0.53 79.50 15 C2a 2 867.8 1.590.79 190.79 159.00 286.19 4.77 0.006 60 0.53 79.50 15 Ex1a 2 867.8 1.590.79 190.79 127.19 317.99 4.77 0.064 90 0.53 79.50 10 Ex2a 10 4911.759.00 4.47 1076.36 719.90 1799.82 27.00 0.36 105 3.00 449.97 10 Ex3a 104932.00 8.94 4.44 1073.21 715.48 1788.69 26.83 0.36 90 2.98 447.19 10

TABLE 2 Common method Step A - Alternative 1 - Characterization ofproduct Item M_(n) M_(w) PDi T_(g) Units g/mol g/mol none ° C. Label Exk l m n C1a 4991 22107 4.43 97 C2a 19048 39989 2.1 71 Ex1a 1736 35892.07 24 Ex2a 2221 4943 2.23 37 Ex3a 2081 4256 2.04 34Common Method Step A—Alternative 2—Process Conditions

TABLE 3a Item High pressure Solvent Solvent Mix Reactor vessel nameamount temp Stryene GMA BA BMA dtBP tBPB feed time Pressure Units noneNone grams ° C. grams Grams grams grams grams grams hours bar Label Exnone SOL1 a′ T′1 b′ c′ dd′ d′ e′ f′ t′1 g′ C3a NO Xylene 219.99 140319.59 213.06 0 0 27.33 20.03 4 1 Ex4a YES Toluene 500.0 150 0 475.3475.3 0 38.0 0 2.5 2.8

TABLE 3b Item More Reactor heat Further Reactor cool Further Solventtemp reaction time temp dtAP dtAP time Hold time Solvent Units Grams °C. mins ° C. grams hours mins grams Label Ex h′ T′2 t′2 T′3 i′ t3 t′4 j′C3a 0 NA 0 NA 0 0 120 0 Ex4a 20.0 150 30 140 38.0 2 90 101.04

TABLE 4 Common method Step A - Alternative 2 - Characterization ofproduct Item Solids M_(n) M_(w) PDi Units % g/mol g/mol none Label Ex k′l′ m′ n′ C3a NM 3123 7497 2.4 Ex4a 60.0 2548 7720 3.0

TABLE 5 Common method Step B Item Polymer Solvent Solvent from A nameamount SunFA TRAP AN M_(n) M_(w) PDi T_(g) Units grams none grams gramsgrams mg KOH/g g/mol g/mol none ° C. Label Ex p SOL2 q r s t u v w x C1b500.0 Toluene 300.34 397.06 3.97 5.9 5856 43337 7.4 26 C2b 500.0 Toluene344.45 531.33 5.31 14.0 44460 233091 5.24 4 C3b 678.0 Xylene 0 450.0 4.513.6 3383 13533 4.0 −14 Ex1b 500.0 Toluene 332.59 492.85 4.93 5.7 27367662 2.8 −12 Ex2b 550.0 Toluene 365.85 542.13 5.42 10.2 2531 11052 4.4−13 Ex3b 1000.0 Toluene 665.18 985.70 9.86 8.9 3601 9044 2.51 −16 Ex4b583.3 Toluene 0 342.0 3.42 4.3 2331.95 19122 8.2 −44 When q is 0 thismeans solvent is present from the previous step (which is removed asdescribed) but no more solvent added in this step

TABLE 6 Common method Step C Item Ingredient Ingredient Polymer from BAtlas G5000 FES77 Name Amount water solids pH Units grams grams gramsNone grams grams % none Label Ex y z aa IGD1 ab ac ad pH2 C1c 97.0 2.4311.76 None 0 76.6 55 5.4 C2c 100.8 2.52 12.22 Dow PnP 10.08 98.03 52.46.3 C3c 112.0 2.8 13.58 None 0 88.5 45 5.0 Ex1c 117.0 2.93 14.18 DowPnP23.90 118.89 45 6.0 Ex2c 100.0 2.50 12.12 Sefose 20.00 95.38 55 5.9 Ex3c500.0 12.50 60.61 None 0 395.08 55.6 6.6 Ex4c 100.07 2.50 12.13 None 079.07 55.0 5.5

TABLE 7 Composition pigment paste PP1 Compound Pigment paste PP1 Water4.8 Dehydran 1293 0.4 Disperbyk 190 0.7 Kronos 2190 24.1

TABLE 8 Application properties of water-based binders Ex Ex 1 Ex 2 C1 C2C3 Ex 1 pigment Ex 2 pigment Ex 3 Ex 4 Binder (wt %) 100 100 100 100 70100 70 100 100 Particle size [nm] 985 555 370 265 n.a. 320 n.a. 380 354Additol VXW4940/water 1:1 2.2 2.2 1.8 1.8 1.4 2.2 1.4 2.2 2.2 PP1 (wt %)— — — — 30 — 30 — — DFT [hr] 1 0.25 1.5 1 1 2 1 2 TFT [hr] 2 0.75 7 3 23.5 2 3.5 G(s) 81.6 73.5 70.1 78.2 76.6 73.8 79.7 82.4 78.4 G(r) 40.019.1 59.3 77.6 72.7 72.6 77.3 78.3 72 Telg. 41.6 54.4 10.8 0.6 3.9 1.22.4 4.1 6.4 G decay (4 d) 1.9 3.4 10.1 4.2 2.4 0.8 0.2 2.1 9.8 G decay(7 d) 1 3.6 13.5 4.6 4.4 5.7 3.9 4.3 13.9 G decay (14 d) 4.6 4.2 26.39.3 4.7 9.4 8.0 9.2 28.3 Initial yellowness [Δb] 3.8 3.1 4.5 4.7 1.0 3.42.2 3.8 3.7 Dark yellowing Δb 6.6 14.6 21.4 6.1 5.7 9.2  3 wks 52° C.Water resistance 30 min after recovery n.d. n.d. n.d. 5/5 4/5 n.d. 4/5n.d. n.d.  1 hr after recovery n.d. n.d. n.d. 4.5/5   3/5 n.d. 3/5 n.d.n.d.  3 hrs after recovery n.d. n.d. n.d. 4/5 1/5 n.d. 2/5 n.d. n.d.Blocking  4 hrs at amb. temp. n.d. n.d. n.d. n.d. 4.5 n.d. 4 n.d. n.d. 2 hrs at 50° C. n.d. n.d.. n.d.. n.d. 4 n.d. 3 n.d.. n.d..Key for Table 6‘DFT’ denotes dust free time defined and measured as described herein‘TFT’ denotes tack free time defined and measured as described herein‘G(r)’ denotes the initial rough gloss value as defined herein (measuredin gloss units 1 day after film formation)‘G(s)’ denotes the initial smooth gloss value as defined herein(measured in gloss units 1 day after film formation)‘Telg.’ denotes the telegraphing value as defined herein in gloss units(i.e. G(s)_ G(r))‘G decay (‘n’ d)’ denotes the gloss decay value as defined herein after‘n’ days (i.e. G(r) minus the rough gloss measured ‘n’ days after filmformation).

The invention claimed is:
 1. An aqueous emulsion, coating compositionthat comprises an autoxidisable vinyl oligomer, wherein: I) saidautoxidisable vinyl oligomer has: i) fatty acid residue in an amountgreater than or equal to 20% by weight of the autoxidisable vinyloligomer; ii) a glass transition temperature (Tg) from −50° C. to +15°C.; iii) an acid value less than 40 mg KOH/g; iv) a weight averagemolecular weight (Mw) from 2,500 to 40,000 g/mol; and v) apolydispersity (PDi) from 2 to 12; and wherein II) said composition has:a) a co solvent content less than 25% by weight of solids; b) a Nmethylpyrrolidone content less than 13% by weight of solids; c) a solidscontent greater than or equal to 38% by the total weight of saidcomposition; d) 38% to 65% of the autoxidisable vinyl oligomer; e) 0 to20% of co-solvent; and f) 15% to 58% of water, wherein the percentagesof d), e) and f) are by weight of the composition and d)+e)+f)=100%, andwherein III) said composition when in the form of a film has atelegraphing value of less than 10 gloss units, wherein the telegraphingvalue is a difference between an initial smooth gloss value of the filmminus an initial rough gloss value of the film, where (1) the initialsmooth gloss value is the gloss when the film is cast on a smooth PVCsubstrate with Rz=1 μm±0.25 μm and the initial rough gloss value is thegloss when the film is cast on a rough PVC substrate with Rz=25 μm±5 μm,wherein Rz is an average of five greatest peak-to-valley separations ina scanned surface area of 1.9×2.5 mm of the PVC substrate as analyzedwith an optical profilometer at a magnification of 2.5; (2) each filmhas a dry film thickness of 52 μm±6 μm; and (3) each initial gloss valueis measured at a 20° angle, 24 hours after the film has been cast ontothe PVC substrate.
 2. The aqueous autoxidisable coating compositionaccording to claim 1, wherein the composition comprises an autoxidisablevinyl oligomer obtained by a process comprising steps of: I)polymerising ethylenically unsaturated vinyl monomers comprising: i) 30%to 70% of at least one monomer G selected fromhydroxylalkyl(meth)acrylates and epoxy functional vinyl monomers; ii)30% to 70% of at least one other ethylenically unsaturated vinylmonomer; and iii) <1% of chlorine containing monomers; where thepercentages are by weight of total monomers; II) reacting the oligomerobtained in step I) with fatty acids having an average iodine value inthe range of 80 to 180 g I2/100 g fatty acid; where the autoxidisablevinyl oligomer has i) oligomeric backbone in an amount from 35% to 62%by weight of the oligomer; ii) fatty acid residue in an amount from 38%to 65% by weight of the oligomer; iii) a Tg from −50 to 15° C.; iv) a Mwfrom 6500 to 25000 g/mol; and v) a PDi from 2 to 8; said compositionhaving a) a co solvent content <15 wt % by weight of solids; b) a Nmethylpyrrolidone content <13 wt % by weight of solids; c) heterocyclicamine containing solvent content of 0 wt % by weight of solids; d) asolids content >38 wt %; e) a pH in the range of from 4.1 to 8.4; andwherein said composition when in the form of a coating has atelegraphing value of less than 10 gloss units.
 3. The aqueousautoxidisable coating composition according to claim 1, wherein 0% ofglycidyl esters of unsaturated fatty acids are used in the preparationof the autoxidisable vinyl oligomer.
 4. The aqueous autoxidisablecoating composition according claim 1, wherein the autoxidisable vinyloligomer, if carboxylic acid functional conforms to the followingrelationship:ND×AV≦22 where ND=neutralization degree of the acid groups on theoligomer and AV=acid value.
 5. The aqueous autoxidisable coatingcomposition according to claim 1, wherein the composition comprises <5%of N methylpyrrolidone by weight of solids.
 6. The aqueous autoxidisablecoating composition according to claim 1, wherein the compositioncomprises <13% by weight of solids, of nitrogen-containing moleculeswith an evaporation rate <0.1 as determined by ASTM D3539 relative tothe evaporation rate of n-butyl acetate=1.00 which are either aromatic,heterocyclic or which are aromatic and aliphatic primary and secondary(di)amines with the proviso that the amount of nitrogen in suchmolecules is >5% by weight of the molecule.
 7. The aqueous autoxidisablecoating composition according to claim 1, wherein said compositioncomprises: i) 20% to 45% of TiO₂; ii) 20% to 45% of the autoxidisablevinyl oligomer; iii) 0 to 10% of co solvent; iv) 0.1% to 3% ofthickener; v) 0 to 5% of dispersing agent; and vi) 25% to 60% water;where the percentages are by weight of the composition andi)+ii)+iii)+iv)+v)=100%.
 8. A method of coating a substrate comprisingthe steps of: i) applying a coating composition as claimed in claim 1 toa substrate; and ii) drying the substrate to form a coating thereon;wherein the coating has a telegraphing value of less than 10 glossunits.